Code review comment for lp:~vlad-lesin/percona-server/5.5-bug-1351148

> - I don't understand the stack_ends_here calculation for the
> #else case. In the first line we round down &tmp to the page
> size, and then we add either 0, either STACK_DIRECTION * stack
> size. Adding zero if STACK_DIRECTION == 1 does not look right?
> It seems the intention was to jump one page if the stack grows
> down, but for that the evaluation precedence is wrong, it needs
> extra parentheses around the ?: operator.

Fixed.